Art of annealing metal work



Aug. 2, 1932. i.. L. L Ewls 398702125 ART OF ANNEALNG METAL WORK Enea Feb. 1v, 1930 "j il 2- -2 J H F151- 2 Patented Aug.. 2, 1932 ,UNiTEn sraras OFFICE,

LESTER L. LEWIS, F NEW CASTLE, PENNSYLVANIA, ASSIGNOB OF TWO-THIRDS T0 BLAIR STRIP STEEL COMPANY, OF NEW CASTLE, PENNSYLVANIA, A. COBPORATIUN 0F PENNSYLVANIA ART' OIF ANNEALING 'METAL WORK Application led February 17, 1930. Serial No. 429,185.

This invention relates to improvements in the art of heat treating and cooling metal Work for increasing ductility without discoloration, and more particularly to the art as set forth in my two co-pending applications, one filed December 2, 1929, designated by Serial No.` 411,179, now Patent No. 1,777,978, dated October 7, 1930, and the other filed February 4, 1930, designated by\ l" Serial No. 425,812, now Patent'No. 1,835,411,

dated December .8, 1931.

The essential object in view is characterl istically similar to' that of the art as set forth in said co-pending applications, and

that object is attained by a modified mode of treatment as Will hereinafter become apparent.

Among the moredetailed objects in View is the securing of a high degree of ductility of the metal Work annealed at a minimum costi, and the maintenance of the superficial condition of the Work substantially or Wholly free from discoloration.

With these and other objects in View as will hereinafter in part become apparent and in part be stated, the invent'on comprises the heat treating or metal work free from' any especial attempt at sealing, and the subsequent cooling of the Work under conditionsy 3 precluding surface discoloration.

The invention comprises certain other novel steps and combinations ofsteps 1n the art of heat treat-ing metal Work as will be hereinafter specified and subsequently par-` ticularly pointed out in the appended clalms.

The invention is adapted to be practiced by the use of any of many well Vknown forms of heat treating apparatus,I and almost any goed set of such apparatus can readily be 40 used; but,.for purposes of'preferred exemplification, any of the structures disclosed in my above-identified colpending applications,

may be effectively use and to the end of clearly and more readily disclosing the invention one of the forms of my secondabove-identied application is illustrated in the accompanying drawin for purposes of concrete reference in the description of the application of the invention, and in which drawing,- y

Figure 1 is a top plan view of a fragment of a. furnace and Work-receiving, movable housing Well adapted for the carrying out of the present invention.

Fi ure 2 is a transverse section taken on the p ane indicated by line 2 2 of Figure 1. Figure 3 is a similar view of the same after removal from the furnace and after preparation for the 'cooling of the metal.

Referring to the drawing bynumerals, 1 irdicates an annealing furnace which may be o any p which vis preferably provided'with the usual antifriction tracks 2, 2, sustaining and directing the Work-carrying housing Vinto and out of the furnace.A r1 ."he work-carrying hous- ,ing may be formed or made up in any preferred or Well known manner, one type of housing in use in standard practice consisting f a tray 3 having grooves 4 in its under face to receive the balls or antifriction devices 2. A casing 5, commonly referred to as an annealing pot, is mounted on the tray 3,- .the pot being of suiliciently reduced dimensions with respect to the upstanding flange 6 of the tray as to leave a groove-like, open space 7 between the side wall of the pot and t e upstanding angef the tray. The work indicated at Sis mounted on the tray 3, and the pot 5 is lowered over the work in the well known or approved type and preparation for the annealing operation. A t

latter is during a part of the operation connected with a gas supply pipe 16. It should be understood that lthe nipplesll and 15 are adapted to be detachably connected with the i to such equipment, but may be more readily disclosed by specific reference to the preferred mani ulation with respect to such equipment.' lWith this understanding in the carrying out of the present invention, work 8 is supplied to the housing made up of tray 3 and pot 5. This work must, however, to

give the best results, be entirely or substan tially free from carbonaceous matter on its surface, such as the presence of certain rolling lubricants containing carbon. Either the work must be rolled dry or rolled with the use of a lubricant wholly free from carbon, or, if a carbonaceous lubricant be employed during rollin the work must be thoroughly cleansed and reed from any deposits of such lubricant before being assembled in the housing as just stated. While it is true that when heat treating iron or steel which has been rolled with Irolling oil containing carbon good results may be obtained, the presence of any appreciable. amount of such oil is livable to produce a spot or area of discoloration, whereas with the total absence of any such lubricant the finished product is bright and reflector-like in appearance similar to polished nickel.

Thev work being thus assembled in the housing and the pot 5 being arranged on the tray 3 to enclose the work, no provision is or need be made to seal the work priorto introduction into the furnace 1. It has reviously been standard practice to provi e a comminuted seal inthe area 7, and sometimes also directly beneath the lower edge ofthe pot 5 beforel the work is introduced into the annealing furnace, but, according to the present invention, such provision or precaution is not at all necessary. Of course, the pot 5 and tray 3 should be free from flaws or cracks which `are liable'to leak during cooling, as f any a preciable leakage in this way would large y detract from the desirable results tobe obtained, and would be liable to produce discoloration yon the surfaces of the work;

When the parts are thus assembled, as indicated in Figure 2, the housing made u of pot 5 and tray 3 is moved along the trac 2 into the furnace 1 where the temperature of the work is raised to the requisite degree and maintained for the required time for effective annealing. Then the work in its casing, as stated, is withdrawn from the furnace. At the time of introduction into the furnace, the pipes 12 and 16 will not have been connected to their respective nipples 11 and 15, but just assoon as the work has been withdrawn from the furnace, the operator deposits a ycomminuted filler orseal into the e area 7, filling the same at least to the level of the discharge openings 10 and 14, and preferably entirely filling the said area up to the level of the upper edge of the flange 6 of tray 3 all about the'pot 5. Itis also preferable to tamp the comminuted material somewhat to insure -a reasonable degree of compactness thereof. When the filler or'seal seen at 17 in Figure 3 has been thus applied, gas under pressure is supplied to the portsv 9 and 13 and caused to discharge through' the openings 10 and 14 under suiicient ressure to effectively resist the tendency o the atmosphere to penetrate Athe comminuted seal 17 in response to the forming vacuum in the-pot 5 with the cooling of the contents of the pot. The comminuted material 17 may be iron filings or iron chips, or sand, and when sand is em loyed, a fine grade free from loam is pre erred, such as commonly referred to as lake sand. The supply pipes 12 and 1 6 may be connected to their respective nipples 11 and 15 at any time convenient to the operatorl relative to the filling of the seal 17 in the area 7 it being understood that the said connections are made and the filling in of the sealing matter completed as `pro'mptl as practicable after the withdrawal of t e parts from the source of heat. The connections must be completed and the gas turned on by the time cooling has progressed to that point Where a partial vacuum begins to form within the pot 5. This does not occur for some little time,"perhaps as much as twenty minutes after the withdrawal of the average pot 5 from the furnace, but

.it is well to have theseal applied and the `pot and tray. While I have illustratedtwo sources 'of gas supply tothe area 7, one in the form of the port 9 and, its discharge 10 and the other in, the form of the port 13 and' its discharge 14, one or the other of these vsources of supply may be successfully omitted, but I prefer the balanced actionj incident to the use of both. i

It is well understood by all workers, in the present art that iron or steel at high temperature oxidizes readily, and, therefore, the cooling operation must progress to the point where the work is below that temperature at which surface discoloration will occur incident to contact with the air before the gas supply is turned 0E from ports 9 and 13 or the housing is opened.

Generic claims for the broader aspects of the process invention of this application are presented in my co-pending application Serial No. 479,051, liled August 30, 1930, as a division of my above-identified application, now Patent No. 1,777,978.

1What is claimed is 1. In the art of annealing metal work, heat treating metal work in an unsealedcontainer of the type admitting passage of atmosphere to and from the interior when unsealed, cooling the work within the container in air,

- sealing the work in the container at the beginning of the cooling step, and maintaining the container completely sealed against discoloration agents until the cooling operation is finished.

2. ln the art of annealing metal work, heat treating metal work in an unsealed condition and sealing the metal work subsequent to the heat treatment, and cooling the sealed yWork in air, and treating the seal during cooling for preventing access of discoloration agents through the seal.

3. ln the art of.annealing metal work, the steps of applying a comminuted seal to the housing for the work subsequent to heat treatment of the work, cooling the work within the housing in air, and distributing gas to the comminuted seal during cooling of the metal work for preventing access of air to the work.

4. In the -art of annealing metal work, the steps recited in claim 3 in which the gas is supplied under pressure suiiicient to counterbalance atmospheric pressure and exclude atmosphere.

5. ln the art of annealing metal work, heat treating metal work to a suiiiciently high degree and for the requisite time for annealing purposes while the work is in an unsealed condition, discontinuing the heat treatment,

and thereafter applying a seal of comminuted material and delivering gas to said seal under pressure sufficient for excludin from the Work discoloration-.producing in uences.

6. ln the art of annealing metal work, preparing metal work for annealing ree from. surface carbon, raising the work to annealing temperature for the requisite time, and subsequently cooling the work within a housing in air, and sealing the housing against ingress of discoloration agents for preserving the work against discoloring action during the cooling operation.

7. ln the art of annealing metal work, preture at which atmospheric contact with the 75 work is liable to produce discoloration.

In testimony whereof I aiix my signature.

LESTER L. LEWIS. 

